Environmental Science Chapter 9 Demographers – study/make human population predictions. 1 to 2 billion took 50 years 2 to 4 billion took 44 years Due to falling birth rates, stabilize around 9 billion by More food and better hygiene contributed most to human population’s exponential growth during the modern age.

Environmental Science Chapter 9 Many people have low literacy and limited access to healthcare which makes it difficult to reduce population growth. Population pyramids – graph the distribution of ages in a population at a specific time. Trends such as when birth rates and death rates are both high, the population grows slowly, it at all.

Environmental Science Chapter to 1930 human population doubled due to: Industrial revolution High birth rates, low death rates Improvements in infrastructure and services Waterborne diseases, such as dysentery were alleviated by having adequate sewage treatment facilities and using fuel wood to boil water to sterilize it.

Environmental Science Chapter 9 Less-developed countries: - suffer more from rapid population growth because they are less likely to have the infrastructure to support the population. -people cut down trees faster than they can grow, making fuel wood a limited resource. -designated by United Nations for priority for foreign aid.

Environmental Science Chapter 9 Age structure, survivorship, fertility rates, and migration are used by scientists to predict population sizes. Populations are growing more rapidly in Peru. World population growth will eventually stop when most countries have replacement-level fertility rates.

Environmental Science Chapter 9 Countries with high growth rates usually have an age structure that has more young people than older people. Immigration – coming “in” Emigration – “exiting” Mathematical statement for population growth. # births + # immigrants > # deaths + # emigrants

Environmental Science Chapter 9 Survivorship – the % of members of a group that are likely to survive to any given age. Increasing life expectancy can result in an increase in population. Life expectancy is mostly influenced by infant mortality. A shortage of arable land can decrease the food supply available to a growing population.

Environmental Science Chapter 9 Population pyramid – used by demographers to predict which age groups will experience the most growth. (future needs anticipated) Advantages for slower population growth -better chance carrying capacity not exceeded -avoid environmental degradation -clean water, adequate sewage disposal -adequate health care and education

Environmental Science Chapter 9 Factors causing abrupt halt in population growth. -sharp increase in death rates -inadequate food supplies -diseases -warfare Infant mortality can be reduced by: -education -adequate food supplies, clean water -fuel for warmth and cooking

Environmental Science Chapter 9 Essay topics. Utilize population pyramids How is population growth contributing to environmental degradation? What are some social problems caused by rapid population growth?